Camera module having rearmost lens with concave image-side surface

ABSTRACT

A camera module includes: an optical imaging system including a frontmost lens disposed closest to an object side, a rearmost lens disposed closest to an imaging plane, and at least one middle lens disposed between the frontmost lens and the rearmost lens. An image-side surface of the rearmost lens is concave and an inflection point is formed on the image-side surface of the rearmost lens. 0.2&lt;D/TTL is satisfied, D being a shortest distance between the rearmost lens and the imaging plane, and TTL being a distance from an object-side surface of the frontmost lens to the imaging plane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/184,264 filed on Jun. 16, 2016, which claims the benefit under 35 USC119(a) of Korean Patent Application No. 10-2015-0164238 filed on Nov.23, 2015, in the Korean Intellectual Property Office, the entiredisclosures of which are incorporated herein by reference for allpurposes.

BACKGROUND 1. Field

The following description relates to a camera module having a hand-shakecompensation function.

2. Description of Related Art

Functions of a camera module for a portable terminal have been graduallyimproved. For example, the camera module includes an optical imagingsystem composed of multiple lenses in order to capture high resolutionimages. In addition, the camera module includes a hand-shakecompensation unit that is operable to prevent an image qualitydeterioration phenomenon due to vibrations.

Camera modules have been gradually miniaturized in accordance with thethinning of portable terminals. However, the miniaturization of opticalimaging systems may cause problems such as a decrease in availablemounting space in the hand-shake compensation unit, and a decrease inmovement space of the optical imaging system by the hand-shakecompensation unit.

Therefore, a camera module capable of being miniaturized and allowingsufficient space for a hand-shake compensation unit to be securedtherein is desirable.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

According to one general aspect, a camera module includes: an opticalimaging system including a frontmost lens disposed closest to an objectside, a rearmost lens disposed closest to an imaging plane, and at leastone middle lens disposed between the frontmost lens and the rearmostlens. An image-side surface of the rearmost lens is concave and aninflection point is formed on the image-side surface of the rearmostlens. 0.2<D/TTL is satisfied, D being a shortest distance between therearmost lens and the imaging plane, and TTL being a distance from anobject-side surface of the frontmost lens to the imaging plane.

The at least one middle lens may include three lenses.

The camera module may further include a hand-shake compensation unitconfigured to move the optical imaging system in a directionintersecting an optical axis of the optical imaging system.

The camera module may further include an auto-focusing unit configuredto move the optical imaging system in an optical axis direction of theoptical imaging system.

D may be greater than 0.9 mm.

TTL/ImgH<0.7 may be satisfied, ImgH being a diagonal length of theimaging plane.

75 degrees<FOV may be satisfied, FOV being a field of view of theoptical imaging system.

According to another general aspect, a camera module includes: anoptical imaging system including lenses, each of the lenses having arefractive power; and an imaging plane on which an image of lightrefracted by the optical imaging system is formed. 0.8 mm<D issatisfied, where D is a shortest distance between an image-side surfaceof a fifth lens of the lenses and the imaging plane. TTL/ImgH<0.7 issatisfied, where TTL is a distance from an object-side surface of afirst lens of the lenses to the imaging plane, and ImgH is a diagonallength of the imaging plane. The first lens is closest to the objectside and the fifth lens is closest to the imaging plane.

The lenses comprise the first lens comprises a positive refractivepower, a second lens having a negative refractive power, a third lenshaving a positive refractive power, a fourth lens having a negativerefractive power, and the fifth lens having a positive refractive power,the first to fifth lenses being sequentially disposed from an objectside to the imaging plane.

The object-side surface of the first lens may be convex.

An object-side surface of the third lens may be concave.

An object-side surface of the fourth lens and an image-side surface ofthe fourth lens may be concave.

The image-side surface of the fifth lens may be concave and aninflection point may be formed on the image-side surface of the fifthlens.

0.24<D/f may be satisfied, f being an overall focal length of theoptical imaging system.

TTL<4.25 mm may be satisfied.

An F number of the optical imaging system may be 2.10 or less.

TTL/ImgH<0.68 may be satisfied.

According to another general aspect, a camera module includes: anoptical imaging system including a frontmost lens having a positiverefractive power, a rearmost lens having a positive refractive power,and middle lenses disposed between the frontmost lens and the rearmostlens; and an imaging plane on which an image of light refracted by theoptical imaging system is formed, the imaging plane being positionedrearward of the rearmost lens. TTL/ImgH is less than 0.7, TTL being adistance from an object-side surface of the frontmost lens to theimaging plane, and ImgH being a diagonal length of the imaging plane.D/f is greater than 0.24, D being a shortest distance between animage-side surface of the rearmost lens and the imaging plane, and fbeing an overall focal length of the optical imaging system.

The middle lenses may include three lenses. One or more of the threelenses may have negative refractive power.

D/TTL may be greater than 0.2.

D may be greater than 0.8 mm.

According to another general aspect, a camera module includes: anoptical imaging system including a first lens positioned closest to anobject side of the optical image system, and a last lens positionedclosest to an image side of the optical imaging system; and an imagingplane on which an image of light refracted by the optical imaging systemis formed. D/f is greater than 0.24, D being a shortest distance betweenan image-side surface of the last lens and the imaging plane, and fbeing an overall focal length of the optical imaging system. TTL is lessthan 4.25 mm, TTL being a distance from an object-side surface of thefirst lens to the imaging plane.

The optical imaging system may further include: a second lens having anegative refractive power; a third lens having a positive refractivepower; and a fourth lens having a negative refractive power, wherein thefirst lens, the second lens, the third lens, the fourth lens and thelast lens are sequentially arranged from the object side to the imagingplane.

The image-side surface of the last lens may be concave and may includean inflection point.

The object-side surface of the first lens may be convex. An object-sidesurface of the second lens may be convex. An object-side surface of thethird lens may be concave. An image-side surface and an object-sidesurface of the fourth lens may be concave.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view of an optical imaging system of a camera module,according to an embodiment.

FIG. 2 includes graphs having curves representing aberrationcharacteristics of the optical imaging system illustrated in FIG. 1 ,according to an embodiment.

FIG. 3 is a graph representing a modulation transfer function (MTF) ofthe optical imaging system illustrated in FIG. 1 , according to anembodiment.

FIG. 4 is a table illustrating respective characteristics of lenses ofthe optical imaging system illustrated in FIG. 1 , according to anembodiment.

FIG. 5 is a table illustrating respective aspherical surfacecoefficients of lenses of the optical imaging system illustrated in FIG.1 , according to an embodiment.

FIG. 6 is a view of an optical imaging system of a camera module,according to another embodiment.

FIG. 7 includes graphs having curves representing aberrationcharacteristics of the optical imaging system illustrated in FIG. 6 ,according to an embodiment.

FIG. 8 is a graph representing a modulation transfer function (MTF) ofthe optical imaging system illustrated in FIG. 6 , according to anembodiment.

FIG. 9 is a table illustrating respective characteristics of lenses ofthe optical imaging system illustrated in FIG. 6 , according to anembodiment.

FIG. 10 is a table illustrating respective aspherical surfacecoefficients of lenses of the optical imaging system illustrated in FIG.6 , according to an embodiment.

FIG. 11 is a view of an optical imaging system of a camera module,according to another embodiment.

FIG. 12 includes graphs having curves representing aberrationcharacteristics of the optical imaging system illustrated in FIG. 11 ,according to an embodiment.

FIG. 13 is a graph representing a modulation transfer function (MTF) ofthe optical imaging system illustrated in FIG. 11 , according to anembodiment.

FIG. 14 is a table illustrating respective characteristics of lenses ofthe optical imaging system illustrated in FIG. 11 , according to anembodiment.

FIG. 15 is a table illustrating respective aspherical surfacecoefficients of lenses of the optical imaging system illustrated in FIG.11 , according to an embodiment.

FIG. 16 is a partially enlarged cross-sectional view of the cameramodule of FIG. 1 , according to an embodiment.

FIG. 17 is a cross-sectional view of the camera module of FIG. 16 ,taken along line I-I of FIG. 16 .

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent to one of ordinary skill inthe art. The sequences of operations described herein are merelyexamples, and are not limited to those set forth herein, but may bechanged as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that are well known toone of ordinary skill in the art may be omitted for increased clarityand conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

Throughout the specification, it will be understood that when anelement, such as a layer, region or wafer (substrate), is referred to asbeing “on,” “connected to,” or “coupled to” another element, it can bedirectly “on,” “connected to,” or “coupled to” the other element orother elements intervening therebetween may be present. In contrast,when an element is referred to as being “directly on,” “directlyconnected to,” or “directly coupled to” another element, there may be noelements or layers intervening therebetween. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be apparent that though the terms first, second, third, etc. maybe used herein to describe various members, components, regions, layersand/or sections, these members, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one member, component, region, layer or section fromanother region, layer or section. Thus, a first member, component,region, layer or section discussed below could be termed a secondmember, component, region, layer or section without departing from theteachings of the disclosed embodiments.

Spatially relative terms, such as “above,” “upper,” “below,” and “lower”and the like, may be used herein for ease of description to describe oneelement's relationship to another element(s) as shown in the figures. Itwill be understood that the spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. For example, if thedevice in the figures is turned over, elements described as “above,” or“upper” other elements would then be oriented “below,” or “lower” theother elements or features. Thus, the term “above” can encompass boththe above and below orientations depending on a particular direction ofthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may be interpreted accordingly.

The terminology used herein is for describing particular embodimentsonly and is not intended to be limiting of the inventive concept. Asused herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”and/or “comprising” when used in this specification, specify thepresence of stated features, integers, steps, operations, members,elements, and/or groups thereof, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,members, elements, and/or groups thereof.

Hereinafter, embodiments will be described with reference to schematicviews illustrating the embodiments. In the drawings, for example, due tomanufacturing techniques and/or tolerances, modifications of the shapeshown may be estimated. Thus, the disclosed embodiments should not beconstrued as being limited to the particular shapes of regions shownherein, for example, to include a change in shape results inmanufacturing. The following embodiments may also be constituted by oneor a combination thereof.

In addition, it is to be noted that in the following description, afirst lens refers to a lens that is the closest to an object (or asubject) and a fifth lens refers to a lens that is the closest to animaging plane (or an image sensor). In the following description, allnumerical values of radii of curvature, thicknesses, TTL, ImgH (adiagonal length of the imaging plane), and focal lengths of lenses areindicated in millimeters (mm). Further, thicknesses of the lenses,intervals between the lenses, and the TTL are distances along an opticalaxis of the lens. Further, in descriptions of lens shapes, the meaningof one surface of the lens being convex is that an optical axis portion(i.e., a paraxial region) of the corresponding surface is convex, andthe meaning of one surface of the lens being concave is that an opticalaxis portion of the corresponding surface is concave. Therefore, even inthe case that it is described that one surface of the lens is convex, anedge portion of the lens may be concave. Likewise, even in the case thatit is described that one surface of the lens is concave, an edge portionof the lens may be convex.

Further, in the present specification, an object-side surface of thelens refers to a surface of the corresponding lens closest to theobject, and an image-side surface of the lens refers to a surface of thecorresponding lens closest to the imaging plane.

An optical imaging system may include a plurality of lenses. Forexample, the optical imaging system may include five lenses. The firstto fifth lenses configuring the optical imaging system may besequentially disposed in a direction from the object side toward theimaging plane. For example, the first lens may be a lens closest to theobject side, and the fifth lens may be a lens closest to the imagingplane.

Next, five lenses configuring the optical imaging system will bedescribed in detail.

The first lens may, for example, have a positive refractive power.

At least one surface of the first lens may be convex. For example, anobject-side surface of the first lens is convex.

The first lens may have an aspherical surface. For example, theobject-side surface and an image-side surface of the first lens areaspherical. The first lens may be formed of a material having high lighttransmittance and excellent workability. For example, the first lens maybe formed of plastic. However, a material of the first lens is notlimited to plastic. For example, the first lens may also be formed ofglass.

The second lens may, for example, have a negative refractive power.

The second lens may have a meniscus shape. For example, an image-sidesurface of the second lens is concave.

The second lens may have an aspherical surface. For example, theimage-side surface of the second lens is aspherical. The second lens maybe formed of a material having high light transmittance and excellentworkability. For example, the second lens is formed of plastic or apolyurethane material. However, a material of the second lens is notlimited to plastic. For example, the second lens may also be formed ofglass.

The second lens may be formed of a material having a high refractiveindex. For example, the refractive index of the second lens may be 1.60or more. The second lens may further have a low Abbe number. Forexample, the Abbe number of the second lens may be 30 or less. Thesecond lens as described above may decrease chromatic aberrations of thefirst lens.

The third lens may, for example, have a positive refractive power.

The third lens may have a meniscus shape. For example, an object-sidesurface of the third lens may be concave.

The third lens may have an aspherical surface. For example, theobject-side surface and an image-side surface of the third lens areaspherical. The third lens may be formed of a material having high lighttransmittance and excellent workability. For example, the third lens maybe formed of plastic or a polyurethane material. However, a material ofthe third lens is not limited to plastic. For example, the third lensmay also be formed of glass.

The fourth lens may, for example, have a negative refractive power.

The fourth lens may have a meniscus shape. For example, an object-sidesurface and an image-side surface of the fourth lens may be concave.

The fourth lens may have an aspherical surface. For example, theobject-side surface and the image-side surface of the fourth lens may beaspherical. The fourth lens may be formed of a material having highlight transmittance and excellent workability. For example, the fourthlens may be formed of plastic or a polyurethane material. However, amaterial of the fourth lens is not limited to plastic. For example, thefourth lens may also be formed of glass.

The fourth lens may be formed of a material having a high refractiveindex. For example, the refractive index of the fourth lens may be 1.60or more. The fourth lens may further have a low Abbe number. Forexample, the Abbe number of the fourth lens may be 30 or less.

The fifth lens may, for example, have a positive refractive power.

The fifth lens may have a meniscus shape. For example, an image-sidesurface of the fifth lens is concave. The fifth lens may also have aninflection point. For example, the inflection point may be formed on theimage-side surface of the fifth lens.

The fifth lens may have an aspherical surface. For example, theimage-side surface and an object-side surface of the fifth lens areaspherical. The fifth lens may be formed of a material having high lighttransmittance and excellent workability. For example, the fifth lens maybe formed of plastic or a polyurethane material. However, a material ofthe fifth lens is not limited to plastic. For example, the fifth lensmay also be formed of glass.

As indicated above, at least one of the first to fifth lenses may havean aspherical shape. According to an example, among the first to fifthlenses, only the fifth lens may have the aspherical shape. Further, atleast one the object-side surface or the image-side surface of the firstto fifth lenses may be aspherical. The aspherical surface of each of thelenses may be represented by Equation 1.

$\begin{matrix}{Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {Ar}^{4} + {Br}^{6} + {Cr}^{8} + {Dr}^{10} + {Er}^{12} + {Fr}^{14} + {Gr}^{16} + {Hr}^{18} + {Jr}^{20}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, c is an inverse of a radius of curvature of thecorresponding lens, K is a conic constant, r is a distance from acertain point on an aspherical surface to an optical axis, A to J areaspherical constants, and Z is a height from the certain point on theaspherical surface to an apex of the corresponding aspherical surface inan optical axis direction.

The camera module may satisfy the following Conditional Expressions:0.2<D/TTL  [Conditional Expression 1]0.8 mm<D  [Conditional Expression 2]0.9 mm<D  [Conditional Expression 3]TTL/ImgH<0.7  [Conditional Expression 4]75 degrees<FOV  [Conditional Expression 5]0.24<D/f  [Conditional Expression 6]TTL<4.25 mm  [Conditional Expression 7]F No.≤2.1  [Conditional Expression 8]In the preceding Conditional Expressions, D is a shortest distancebetween an image-side surface of the lens closest to an imaging planeand the imaging plane, TTL is a distance from the an object-side surfaceof the lens closest to the object to the imaging plane, ImgH is thediagonal length of the imaging plane, FOV is a maximum field of view ofthe optical imaging system, and f is an overall focal length of theoptical imaging system.

The camera module satisfying the above Conditional Expressions isminiaturized to thereby be mounted on a small sized terminal. Inaddition, the camera module satisfying the above Conditional Expressionsmay realize high resolution in capturing images. Further, the cameramodule satisfying the above Conditional Expressions may be sufficientlycompact to provide a space between the optical imaging system and theimaging plane that is large enough to enable a hand-shake compensationunit to be mounted in the space.

Hereinafter, optical imaging systems according to several exampleembodiments will be described.

FIG. 1 illustrates a camera module 100, according to an embodiment. Thecamera module 100 includes an optical imaging system 110, a filter 120,and an imaging plane 130. The optical imaging system 110 includes aplurality of lenses having refractive power. For example, the opticalimaging system 110 includes a first lens 111, a second lens 112, a thirdlens 113, a fourth lens 114, and a fifth lens 115.

In the camera module 100, the optical imaging system 110 may move in adirection intersecting an optical axis. For example, a shortest distanceD from the fifth, rearmost lens 115 of the optical imaging system 110 tothe imaging plane 130 may be about 0.8 mm or more. For example, theshortest distance D may be about 0.9 mm or more. The numerical value ofD may be a minimum value enabling movement of the optical imaging system110 while enabling disposition of the filter 130 between the fifth,rearmost lens 115 and the imaging plane 130. For reference, in theembodiment of FIG. 1 , the shortest distance D is about 0.908 mm.

The first lens 111 has positive refractive power. An object-side surfaceof the first lens 111 is convex and an image-side surface of the firstlens 111 is convex.

The second lens 112 has negative refractive power. An object-sidesurface of the second lens 112 is convex and an image-side surface ofthe second lens 112 is concave.

The third lens 113 has positive refractive power. An object-side surfaceof the third lens 113 is concave and an image-side surface of the thirdlens 113 is convex.

The fourth lens 114 has negative refractive power. An object-sidesurface and an image-side surface of the fourth lens 114 are concave.

The fifth lens 115 has positive refractive power. An object-side surfaceof the fifth lens 115 is convex and an image-side surface of the fifthlens 115 is concave. The fifth lens 115 may include one or moreinflection points on its object-side surface and its image side-surface.

The optical imaging system 110 further include a stop ST that isoperable to adjust an amount of light incident in the optical system110. The stop ST may be disposed between the second and third lenses 112and 113.

The optical imaging system 110 as described above may exhibit aberrationcharacteristics and MTF characteristics as illustrated in FIGS. 2 and 3. FIGS. 4 and 5 are tables providing example characteristics of lensesand aspherical characteristics of the optical imaging system 110. InFIGS. 4 and 5 the reference characters S1 through S14 refer to thefollowing surfaces in the optical imaging system 110:

S1 and S2: object-side surface and image-side surface, respectively, offirst lens 111

S3 and S4: object-side surface and image-side surface, respectively, ofsecond lens 112

S5: stop ST

S6 and S7: object-side surface and image-side surface, respectively, ofthird lens 113

S8 and S9: object-side surface and image-side surface, respectively, offourth lens 114

S10 and S11: object-side surface and image-side surface, respectively,of fifth lens 115

S12 and S13: object-side surface and image-side surface, respectively,of filter 120

S14: imaging plane 130

An effective radius of the optical imaging system 110 may decrease fromthe first lens 111 toward the stop ST, but may increase from the stop STtoward the imaging plane 130, as illustrated in FIG. 4 . A maximumeffective radius of the optical imaging system 110 may be about 3.133mm, greater than ½ of a diagonal length ImgH of the imaging plane 130.

FIG. 6 illustrates a camera module 200, according to another embodiment.The camera module 200 includes an optical imaging system 210, a filter220, and an imaging plane 230. The optical imaging system 210 includes aplurality of lenses having refractive power. For example, the opticalimaging system 210 includes a first lens 211, a second lens 212, a thirdlens 213, a fourth lens 214, and a fifth lens 215.

In the camera module 200, the optical imaging system 210 may move in adirection intersecting the optical axis. For example, a shortestdistance D from the fifth, rearmost lens 215 of the optical imagingsystem 210 to the imaging plane 230 may be about 0.8 mm or more. Forexample, the shortest distance D may be about 0.9 mm or more. Thenumerical value is a minimum value enabling movement of the opticalimaging system 210 while enabling disposition of the filter 230 betweenthe fifth, rearmost lens 215 and the imaging plane 230. For reference,in the embodiment of FIG. 6 , the shortest distance D is about 0.918 mm.

The first lens 211 has positive refractive power. An object-side surfaceof the first lens 211 is convex, and an image-side surface of the firstlens 211 is concave.

The second lens 212 has negative refractive power. An object-sidesurface of the second lens 212 is convex, and an image-side surface ofthe second lens 212 is concave.

The third lens 213 has positive refractive power. An object-side surfaceof the third lens 213 is concave, and an image-side surface of the thirdlens 213 is convex.

The fourth lens 214 has negative refractive power. An object-sidesurface and an image-side surface of the fourth lens 214 are concave.

The fifth lens 215 has positive refractive power. An object-side surfaceof the fifth lens 215 is convex, and an image-side surface of the fifthlens 215 is concave. The fifth lens 215 may include one or moreinflection points on its object-side surface and its image side-surface.

The optical imaging system 210 may further include a stop ST operable toadjust an amount of light incident in the optical imaging system 210.The stop ST may be disposed between the second and third lenses 212 and213.

The optical imaging system 210 as described above may exhibit aberrationcharacteristics and MTF characteristics as illustrated in FIGS. 7 and 8. FIGS. 9 and 10 are tables providing example characteristics of lensesand aspherical characteristics of the optical imaging system 110. Thesurfaces S1-S14 in FIGS. 9 and 10 correspond to the surfaces S1-S14 inFIGS. 4 and 5 .

An effective radius of the optical imaging system 210 may decrease fromthe first lens 211 toward the stop ST, but may increase from the stop STtoward the imaging plane 230, as illustrated in FIG. 9 . A maximumeffective radius of the optical imaging system 210 may be about 3.133mm, greater than ½ of a diagonal length ImgH of the imaging plane 230.

FIG. 11 shows a camera module 300, according to another embodiment. Thecamera module 300 includes an optical imaging system 310, a filter 320,and an imaging plane 330. The optical imaging system 310 includes aplurality of lenses having refractive power. For example, the opticalimaging system 310 includes a first lens 311, a second lens 312, a thirdlens 313, a fourth lens 314, and a fifth lens 315.

In the camera module 300, the optical imaging system 310 may move adirection intersecting the optical axis. For example, a shortestdistance D from the fifth, rearmost lens 315 of the optical imagingsystem 310 to the imaging plane 330 may be about 0.8 mm or more. Forexample, the shortest distance D may be about 0.9 mm or more. Thenumerical value may be a minimum value enabling movement of the opticalimaging system 310 while enabling disposition of the filter 330 betweenthe fifth, rearmost lens 315 and the imaging plane 330. For reference,in the embodiment of FIG. 11 , the shortest distance D is about 0.919mm.

The first lens 311 has positive refractive power. An object-side surfaceof the first lens 311 is convex, and an image-side surface of the firstlens 311 is concave.

The second lens 312 has negative refractive power. An object-sidesurface of the second lens 312 is convex, and an image-side surface ofthe second lens 312 is concave.

The third lens 313 has positive refractive power. An object-side surfaceof the third lens 313 is concave, and an image-side surface of the thirdlens 313 is convex.

The fourth lens 314 has negative refractive power. The object-sidesurface and the image-side surface of the fourth lens 314 are concave.

The fifth lens 315 has positive refractive power. An object-side surfaceof the fifth lens 315 is convex, and an image-side surface of the fifthlens 315 is concave. The fifth lens 315 may include one or moreinflection points on its object-side surface and its image side-surface.

The optical imaging system 310 may further include a stop ST operable toadjust an amount of light incident in the optical imaging system 310.The stop ST may be disposed between the second and third lenses 312 and313.

The optical imaging system 310 as described above may exhibit aberrationcharacteristics and MTF characteristics as illustrated in FIGS. 12 and13 . FIGS. 14 and 15 are tables providing example characteristics oflenses and aspherical characteristics of the optical imaging system 310.The surfaces S1-S14 in FIGS. 14 and 15 correspond to the surfaces S1-S14in FIGS. 4 and 5 .

An effective radius of the optical imaging system 310 may decrease fromthe first lens 311 toward the stop ST, but may increase from the stop STtoward the imaging plane 330, as illustrated in FIG. 14 . A maximumeffective radius of the optical imaging system may be about 3.120 mm,equal to ½ of a diagonal length ImgH of the imaging plane 330.

Table 1 includes values of optical characteristics and ConditionalExpressions of the optical imaging systems 110, 210 and 310, accordingto the example embodiments. In Table 1, all lengths are indicated inmillimeters (mm). As shown in Table 1, an overall focal length f of theoptical imaging system 110/210/310 may be configured within a range ofabout 3.50 mm to about 3.90 mm. A focal length f1 of the first lens maybe configured within a range of about 2.20 mm to about 2.40 mm. A focallength f2 of the second lens may be configured within a range of about−4.70 mm to about −4.10 mm. A focal length f3 of the third lens may beconfigured within a range of about 16 mm to about 29 mm. A focal lengthf4 of the fourth lens may be configured within a range of about −11 mmto about −8.0 mm. A focal length f5 of the fifth lens may be configuredwithin a range of about 70 mm to about 130 mm. An overall length of theoptical imaging system may be about 4.20 mm or less. A maximum field ofview of the optical imaging system may be about 78 mm or more. D may beabout 0.8 mm or more. However, it may be more advantageous in mounting ahand-shake compensation unit if D is about 0.9 mm or more. The F No. maybe about 2.1 or less. TTL/ImgH may be smaller than about 0.7. However,TTL/ImgH may be smaller than about 0.68, which may be advantageous inminiaturizing the optical imaging system.

TABLE 1 First Second Third Remarks Embodiment Embodiment Embodiment f3.6965 3.7577 3.7341 f1 2.3464 2.3717 2.3717 f2 −4.2246 −4.5776 −4.5776f3 17.1792 27.5840 27.5840 f4 −9.6898 −9.1597 −9.1597 f5 125.476476.3495 76.3495 TTL 4.1969 4.1953 4.1953 BFL 1.0730 1.0690 1.0680 F No.2.070 2.100 2.900 FOV 79.200 78.000 78.000 ImgH 6.240 6.240 6.240 D0.9080 0.9190 0.9180 D/TTL 0.2164 0.2191 0.2188 TTL/ImgH 0.6726 0.67230.6723 D/f 0.2456 0.2446 0.2458

Next, a configuration of an actuator of the camera module 100 will bedescribed with reference to FIGS. 16 and 17 . It should be understoodthat the described configuration of the actuator also applies to thecameral modules 200 and 300.

As shown in FIGS. 16 and 17 , the camera module 100 includes an actuatoroperable to move the optical imaging system 110. For example, the cameramodule 100 includes an auto-focusing unit 160 and a hand-shakecompensation unit 170.

The auto-focusing unit 160 is operable to move the optical imagingsystem 110 in the optical axis direction. To this end, the auto-focusingunit 160 includes a first magnet 162 and a first coil 164. The firstmagnet 162 is disposed on a lens barrel 140 accommodating the opticalimaging system 110 therein, and the first coil 164 is disposed on ahousing 150 accommodating the lens barrel 140 therein. The first magnet162 and the first coil 164 are disposed on one side surface of the lensbarrel 140 and one side surface of the housing 150, respectively, toface each other as illustrated in FIG. 17 .

The hand-shake compensation unit 170 is operable to move the opticalimaging system 110 in the direction intersecting the optical axis. Tothis end, the hand-shake compensation unit 170 includes a second magnet172 and a second coil 174. The second magnet 172 is disposed on the lensbarrel 140 accommodating the optical imaging system 110 therein, and thesecond coil 174 is disposed on the housing 150 accommodating the lensbarrel 140 therein. In more detail, the second magnet 172 and the secondcoil 174 are disposed on another side surface of the lens barrel 140 andanother side surface of the housing 150, respectively, on which theauto-focusing unit 160 is not disposed, to face each other asillustrated in FIG. 17 .

In the camera module 100 as described above, since the overall length ofthe optical imaging system 110 may be about 4.20 mm or less, the cameramodule 100 may be miniaturized. Further, since a sufficient space may beprovided between the optical imaging system 110 and the imaging plane130, the auto-focusing unit 160 and the hand-shake compensating unit 170may be mounted in the space. Therefore, according to the disclosedembodiments, a camera module having high resolution and high performancemay be provided.

As set forth above, according to example embodiments disclosed herein, athin camera module may be provided.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner, and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. A camera module comprising: an optical imagingsystem comprising a frontmost lens disposed closest to an object side, arearmost lens disposed closest to an imaging plane, and at least threemiddle lenses disposed between the frontmost lens and the rearmost lens,wherein an image-side surface of the rearmost lens is concave at anoptical axis of the optical imaging system and an inflection point isformed on the image-side surface of the rearmost lens, and whereinTTL<4.25 mm and 0.2<D/TTL are satisfied, D being a shortest distancebetween the rearmost lens and the imaging plane, and TTL being adistance from an object-side surface of the frontmost lens to theimaging plane.
 2. The camera module of claim 1, wherein the at leastthree middle lenses comprises exactly three lenses.
 3. The camera moduleof claim 1, further comprising: a hand-shake compensation unitconfigured to move the optical imaging system in a directionintersecting the optical axis of the optical imaging system.
 4. Thecamera module of claim 1, further comprising: an auto-focusing unitconfigured to move the optical imaging system along an optical axisdirection of the optical imaging system.
 5. The camera module of claim1, wherein D is greater than 0.9 mm.
 6. The camera module of claim 1,wherein TTL/ImgH<0.7 is satisfied, ImgH being a diagonal length of theimaging plane.
 7. The camera module of claim 1, wherein 75 degrees<FOVis satisfied, FOV being a field of view of the optical imaging system.8. The camera module of claim 1, wherein the rearmost lens is closest tothe imaging plane with respect to all lenses in the optical imagingsystem.
 9. The camera module of claim 8, wherein the rearmost lens haspositive refractive power.